This proposal consists of six projects which relate to the structure and function of the gastrointestinal tract and to the pathogenesis of its disease. The following will be studied: 1. The apoproteins of human intestinal absorptive cells: an immunomorphological analysis. 2. Effect of luminal phospholipids on linoleate transport by intestinal absorptive cells. 3. Influence of short-chain fatty acids and H ion on intestinal absorption. 4. Metabolism of poorly absorbed carbohydrate by the human intestine. 5. Rectal biopsy studies in inflammatory bowel disease. 6. The structure and function of the gastrointestinal tract in disorders of intestinal propulsion.